Process and system for flattening secondary edgebeads on resist coated wafers

Abstract

A method and system of flattening resist mounds formed during a wet edgebead operation. The wet edgebead operation is used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer. Solvent is introduced to the semiconductor wafer at the area containing the resist mounds to soften them, and the semiconductor wafer is spun at a high speed to flatten the mounds.

What is claimed is: 
     
       1. A method of flattening resist mounds formed during a wet edgebead operation, the wet edgebead operation used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer, the method comprising the steps of: (a) introducing solvent to the semiconductor wafer at an area containing the resist mounds to soften the resist mounds while spinning the semiconductor wafer at a rate from approximately 250 to 500 revolutions per minute; and   (b) spinning the semiconductor wafer at a rate of aboat 3000 revolutions per minute or higher to flatten the resist mounds.   
     
     
       2. A method according to claim 1, wherein said steps (a) and (b) are performed simultaneously. 
     
     
       3. A method according to claim 1, wherein said step (b) is performed as the rate at which the semiconductor wafer is spun is increased from the rate in said step (a). 
     
     
       4. A method according to claim 1, wherein said step (b) is performed as the rate at which the semiconductor wafer is spun is increased from the approximately 250-500 revolutions per minute in said step (a). 
     
     
       5. A method according to claim 1, wherein said step (a) further comprises the step of introducing the solvent to the semiconductor wafer at the area containing the resist mounds while spinning the semiconductor wafer at a relatively low rate for a first time interval, and wherein said step (b) further comprises the step of spinning the semiconductor wafer at the rate higher than the relatively low rate for a second time interval.   
     
     
       6. A method according to claim 1, wherein said step (a) further comprises the step of introducing the solvent to the semiconductor wafer at the area containing the resist mounds while spinning the semiconductor wafer at a relatively low rate for a first time interval, and wherein said spinning step (b) further comprises the steps of:   (b1) introducing a second solvent to the semiconductor wafer at a second area while spinning the semiconductor wafer at a higher rate for a second time interval; and   (b2) spinning the semiconductor wafer at the higher rate for a third time interval.   
     
     
       7. A method according to claim 1, further comprising the steps of: (c) exposing the resist material deposited onto the semiconductor wafer to light in accordance with a prescribed pattern; and   (d) developing the resist material deposited onto the semiconductor wafer for device implantation in accordance with the pattern exposed in said exposing step (c).   
     
     
       8. A method of flattening resist mounds formed during a wet edgebead operation, the wet edgebead operation used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer, the method comprising the steps of: (a) introducing solvent to the semiconductor wafer at an area containing the resist mounds to soften the resist mounds while spinning the semiconductor wafer at a rate from approximately 250 to 500 revolutions per minute; and   b) spinning the semiconductor wafer at a rate sufficient to flatten the resist mounds wherein the rate at which the semiconductor is spun in step (b) is increased from the rate of appromixmately 250 to 500 revolutions per minute in step (a).   
     
     
       9. A method according to claim 8, wherein said steps (a) and (b) are performed simultaneously. 
     
     
       10. A method according to claim 8, wherein step (a) further comprises the step of introducing the solvent to the semiconductor wafer at the area while spinning the semiconductor wafer at a relatively low rate for a first time interval, and wherein said step (b) further comprises the step of spinning the semiconductor wafer at the rate higher than the relatively low rate for a second time interval.   
     
     
       11. A method according to claim 8, wherein said step (a) further comprises the step of introducing the solvent to the semiconductor wafer at the area while spinning the semiconductor wafer at a relatively low rate for a first time interval, and wherein said spinning step (b) further comprises the steps of: (b1) introducing a second solvent to the semiconductor wafer at a second area while spinning the semiconductor wafer at a higher rate for a second time interval; and   (b2) spinning the semiconductor wafer at the higher rate for a third time interval.     
     
     
       12. A method according to claim 8, further comprising the steps of: (c) exposing the resist material deposited onto the semiconductor wafer to light in accordance with a prescribed pattern; and   (d) developing the resist material deposited onto the semiconductor wafer for device implantation in accordance with the pattern exposed in said exposing step (c).   
     
     
       13. A method of flattening resist mounds formed during a wet edgebead operation, the wet edgebead operation used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer, the method comprising the steps of: (a) introducing solvent to the semiconductor wafer at an area containing the resist mounds to soften the resist mounds while spinning the semiconductor wafer at a first rate from approximately 250 to 500 revolutions per minute; and   (b) spinning the semiconductor wafer from the first rate to a second rate substantially higher than the first rate while the solvent is introduced to the semiconductor wafer at a rate sufficient to flatten the resist mounds.   
     
     
       14. A method of flattening resist mounds formed during a wet edgebead operation, the wet edgebead operation used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer, the method comprising the steps of: (a) spinning the semiconductor wafer while the solvent is simultaneously introduced to the semiconductor wafer at a rate sufficient to flatten the resist mounds; and   (b) exposing the flattened resist mounds deposited onto the semiconductor wafer edge to light to remove the flattened resist mounds.   
     
     
       15. A method of flattening resist mounds formed during a wet edgebead operation, the wet edgebead operation used to remove edgebeads formed when a resist material is deposited on a semiconductor wafer, the method comprising the steps of: (a) spinning the semiconductor wafer while the solvent is simultaneously introduced to the semiconductor wafer at a rate of approximately 3000 revolutions per minute or higher to flatten the resist mounds; and   (b) exposing the flattened resist mounds deposited onto the semiconductor wafer edge to light to remove the flattened resist mounds.